• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.2
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• pp.112-125
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• 2015

Making a model that is an accurate replica of the oral structure requires precision and efficiency. Nowadays, rapid technological advances bring digitalization in dentistry. One of the most important works in digital dentistry is three-dimensional modeling of the oral cavity and digitizing the 3D data. Among the three components of CAD/CAM, (1) data capture component (digitizers), (2) design component (CAD software), (3) manufacturing component (CAM), the basic component that has a significant impact on the other processes is the data capture component, i.e. intra-oral scanners. This literature review discusses the principles and clinical use of intra-oral scanners in dentistry based on recent publications of the past 5 years using the PubMed and Google Scholar databases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3007-3013
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• 2014

The objectives of this study was to evaluate the validity of 3D digital models made from blue LED dental scanner. Twenty same cases of stone models and 3d digital models were manufactured for this study. Intercanine distance, intermolar distance, two dental arch lengths(right, left) and two diagonal of dental arch lengths(right, left) were measured for evaluation of validity. The nonparametric Wilcoxon rank sum test was used for statistical analysis (${\alpha}$=0.05). Although stone models showed larger than digital models in all measured distances(p<0.05), none exceeded the clinically acceptable range.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.2
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• pp.55-63
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• 2019

The aim of this article was to review various methods used to evaluate the accuracy of digital dental models. When evaluating the accuracy of digital models, the errors can be reduced by educating examiners and using artificial landmarks. The accuracy evaluation methods of digital dental models are divided into linear measurement, 2-dimensional cross-sectional analysis, and 3-dimensional best fit measurement. As the technology of scanners develops, many studies have been conducted to compare the accuracy of digital impression and conventional impression. According to improvement of scan technologies and development of 3-dimensional model analysis software, the ability to evaluate the accuracy of digital models is becoming more efficient. In this article, we describe the methods for evaluating the accuracy of a digital model and investigate effective accuracy analysis methods for each situation.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.275-276
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• 2016

토공 작업현장의 정확한 계측을 위해 3차원 스캐너(Terrestrial Laser Scanner, TLS)의 이용이 점차 확대되고 있으며, 스캐너를 통해 취득한 원지형 디지털 정보를 건설기계 장비 자동화를 위한 기초자료로 활용하는 연구가 이루어지고 있다. 3차원 지형정보를 취득하기 위해서는 현장측정 및 후처리작업이 필요하며, 현장측정과 후처리를 위한 방법 선택에 따라, 측정 정밀도 및 소요시간이 달라진다. 본 연구에서는 최적 스캐닝 플랫폼 구축을 위해 현장측정 및 후처리 방법에 따라 변화하는 정밀도 및 생산성을 계측 분석하는 방법을 제안하였다.

• The KIPS Transactions:PartA
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• v.14A no.3 s.107
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• pp.133-140
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• 2007

The SWBF(shrink-wrapped boundary face) algorithm is a recent mesh reconstruction method for constructing a surface model from a set of unorganized 3D points. In this paper, we point out the surface duplication problem of SWBF and propose an improved mesh reconstruction scheme. Our method tries to classify the non-boundary cells as the inner cell or the outer cell, and makes an initial mesh without surface duplication by adopting the improved boundary face definition. To handle the directional unbalance of surface sampling density arise in typical 3D scanners, two dimensional connectivity in the cell image is introduced and utilized. According to experiments, our method is proved to be very useful to overcome the surface duplication problem of the SWBF algorithm.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.6
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• pp.539-544
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• 2013

In this paper, we was designed three-dimensional face recognition algorithm using polynomial based RBFNNs and proposed method to calculate the recognition performance. In case of two-dimensional face recognition, the recognition performance is reduced by the external environment like facial pose and lighting. In order to compensate for these shortcomings, we perform face recognition by obtaining three-dimensional images. obtain face image using three-dimension scanner before the face recognition and obtain the front facial form using pose-compensation. And the depth value of the face is extracting using Point Signature method. The extracted data as high-dimensional data may cause problems in accompany the training and recognition. so use dimension reduction data using PCA algorithm. accompany parameter optimization using optimization algorithm for effective training. Each recognition performance confirm using PSO, DE, GA algorithm.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.1
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• pp.77-84
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• 2020

This study is apply 3D spatial information per traditional landscape space by comparing spatial information data created using a small drone and 3D scanner used for 3D spatial information construction for efficient preservation and management of traditional landscaping space composed of areas such as scenic sites and traditional landscape architectures. The analysis results are as follows. First, aerial photogrammetry data is less accurate than 3D scanners, but it was confirmed to be more suitable for monitoring landscape changes by reading RGB images than 3D scanners by texture mapping using digital data in constructing orthographic image data. Second, the orthographic image data constructed by aerial photogrammetry in a traditional landscaping space consisting of a fixed area, such as Gwanghalluwon Garden, produced visually accurate and precise results. However, as a result of the data extraction, data for trees, which is one of the elements that make up the traditional landscaping, was not extracted, so it was determined that 3D scanning and aerial surveying had to be performed in parallel, especially in areas where trees were densely populated. Third, The surrounding trees in Soswaewon Garden caused many errors in 3D spatial information data including topographic data. It was analyzed that it is preferable to use 3D scanning technology for precise measurement rather than aerial photogrammetry because buildings, landscaping facilities and trees are dense in a relatively small space. When 3D spatial information construction data for a traditional landscaping space composed of area using a small drone and a 3D scanner free from temporal and spatial constraints and compared the data was compared, the aerial photogrammetry is effective for large site such as Hahoe Village, Gyeongju and construction of a 3D space using a 3D scanner is effective for traditional garden such as Soswaewon Garden.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.60-69
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• 2016

Purpose: The objective of this study was to compare the accuracy of digital models from 3 dimentional (3D) optical scanner and cone beam computed tomography (CBCT). Materials and Methods: We obtained digital models from 11 pairs of stone casts using a 3D optical scanner and a CBCT, and compared the accuracy of the models. Results: The error range of average positive distance was 0.059 - 0.117 mm and negative distance was 0.066 - 0.146 mm. Statistically (P < 0.05), average positive distance was larger than $70{\mu}m$ and shorter than $100{\mu}m$, and that of negative distance was larger than $100{\mu}m$ and shorter than $120{\mu}m$. Conclusion: We concluded that the accuracy of digital models generated from CBCT is not appropriate to make final prostheses. However, it may be acceptable for provisional restorations and orthodontic diagnoses with respect to the accuracy of the digitalization.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.10a
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• pp.141-142
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• 2010

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.79-80
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• 2014

본 논문에서는 다방향 패턴을 이용한 구조광(structured light)방식의 3차원 스캔 기법을 적용하여 3차원 스캐너의 3차원 형상 취득의 정밀도를 높이는 방법을 제안한다. 기존의 단방향 패턴을 이용한 3차원 구조광 방식의 스캔 기법으로 3차원 형상을 취득하는 경우, 스캔 대상 표면의 법선벡터가 패턴의 방향과 수평 할수록 부정확한 형상이 복원된다. 본 논문에서는 스캔 대상의 경사면에 따른 법선 벡터(normal vector) 검출 및 검출된 벡터를 통한 최적의 패턴 방향 선출(quantization), 그리고 각 화소의 최적의 패턴방향을 이용한 선별적인 구조광 방식의 3차원 스캔 기법을 통하여 3차원 형상 취득의 정확성을 높이는 기법을 제안한다.